Genetic Diversity and Virulence Potential of Staphylococcus aureus Isolated from Crayfish (Procambarus clarkii).

Staphylococcus aureus, a commensal and a pathogenic bacterium, causes a wide variety of diseases in humans and animals with a high impact on public health and the livestock industry. The risk of zoonotic transmission to humans highlights the need to understand the molecular ecology of S. aureus in foods. In this study, we obtained 25 S. aureus isolates from 39 crayfish samples in Hubei, China. PCR was applied for detection of presence of virulence and methicillin resistance genes in the pathogen genome. The result revealed that all of the 25 S. aureus isolates harbored at least four virulence genes, and 64 % of them were positive for five or more virulence genes. The most predominant virulence genes were coa, α-HL and ß-HL genes (100 %), followed by sea (68 %), fnbA (60 %), tsst-1 (36 %), while none of the examined isolates presented positive for mecA gene conferring methicillin resistance. Subsequently, all of the isolates were assessed for phenotypic biofilm formation with the microtiter plate assay. The results showed 92 % isolates could produce biofilm with different forming capacity. Multilocus sequence typing divided the isolates into five sequence types (STs), three of which (ST1920, ST188 and ST398) were the same with the isolates from livestock and clinic in China. This study provides preliminary insights into the genetic diversity and virulence gene profiles of S. aureus from crayfish, suggesting that S. aureus isolates from crayfish is a potential hazard for consumers and deserves further attention.

[Prediction Model of Groundwater Sulphate Based on Combined Multi-source Spatio-temporal Data].

The accurate prediction of spatial variation trends in groundwater SO42- is of great significance for improving groundwater quality and regional groundwater management level. The multi-source spatio-temporal data such as land cover data, soil parameter data, digital elevation data, and groundwater pH value in the plain area of the Yarkant River Basin in 2011, 2014, 2017, and 2020 were used as characteristic variables to analyze their correlation with groundwater SO42- concentration. To enhance the prediction accuracy, the Bayesian optimization algorithm (BOA) was used to optimize the random forest regression (RFR). Based on the BOA-RFR model, the importance of the characteristic variables was analyzed, the prediction accuracy of the model was evaluated, and the groundwater SO42- prediction map was generated. The results showed that pH value, ground elevation (GE), and percentage of bare land (BAR) in the contribution area were important parameters influencing groundwater hydrochemical composition, which were significantly negatively correlated with groundwater SO42- concentration, and the importance of impact factors for predicting groundwater SO42- concentration exceeded 25 %. The geostatistical interpolation method was used as an auxiliary tool for the predictive modeling of spatial distribution. After adding auxiliary samples, the R2 of groundwater SO42- concentration prediction of the BOA-RFR model was greater than 0.96, and the maximum values of RMSE and MAE were reduced by 4.7 % and 23.8 %, respectively, compared with the minimum values of the model with fewer samples. The SO42- concentration prediction map showed that high SO42- groundwater was enriched in the northeast of the plain area of the Yarkand River Basin, an area that was expanding.

[Groundwater Pollution Risk Assessment in Plain Area of the Yarkant River Basin].

Groundwater pollution risk assessment is an effective method to manage groundwater resources and prevent groundwater pollution. The DRSTIW model was used to evaluate the groundwater vulnerability in a plain area of the Yarkant River Basin, and factor analysis was used to identify pollution sources for pollution loading evaluation. The functional value of groundwater was estimated by considering both the mining value and the in-situ value. The entropy weight method and the analytic hierarchy process (AHP) were used to determine the comprehensive weight, and a groundwater pollution risk map was generated based on the overlay function of ArcGIS software. The results showed that the natural geological factors such as large groundwater recharge modulus, wide recharge sources, strong permeability of soil surface and unsaturated zone, and shallow groundwater depth facilitated pollutant migration and enrichment, resulting in a higher overall groundwater vulnerability. Very high vulnerability and high vulnerability areas were mainly distributed in Zepu County, Shache County, Maigaiti County, Tumushuke City, and the eastern part of Bachu County. The pollution loading of groundwater was generally low, the main pollution sources were point source pollution caused by water-rock interaction, non-point source pollution caused by pesticides and fertilizers, and point source pollution caused by industry and life. The overall functional value of groundwater was low because of human economic activities, fine water quality, and good habitat quality. Groundwater pollution risk was generally low, and very high and high pollution risk areas accounted for 20.7% of the study area, mainly distributed in Shache County, Zepu County, Maigaiti County, Tumushuke City, and the western part of Bachu County. Natural conditions such as strong aquifer permeability, weak groundwater runoff conditions, large groundwater recharge modulus, low vegetation coverage, and strong water-rock interaction, coupled with frequent human activities such as application of agricultural fertilizers and discharge of industrial and domestic sewage, made the groundwater pollution risk higher in these areas. Groundwater pollution risk assessment provided strong data support for the optimization of the groundwater monitoring network and the prevention of groundwater pollution.

[Groundwater Pollution Risk Assessment in Plain Area of Barkol-Yiwu Basin].

Groundwater pollution risk assessment is an important part of groundwater pollution prevention and control. Taking groundwater in the plain area of Barkol-Yiwu Basin as the research object, the DRSTIW model was constructed to evaluate groundwater vulnerability. According to the survey data of contaminated sites and land use types, point source and non-point source pollutions were classified, and the groundwater pollution load was evaluated. The primary value, economic value, and ecological value of groundwater were considered to evaluate the functional value of groundwater. The groundwater pollution risk assessment map was generated by using the map algebra function of ArcGIS software. The ROC curve was used to verify the risk assessment results of groundwater pollution. The spatial distribution of cold and hot spots of groundwater pollution risk was obtained by calculating the G index, and the change in hot spots was quantitatively analyzed by combining the center of gravity and standard deviation ellipse. The results showed that the groundwater vulnerability was generally low. The gentle terrain slope, shallow groundwater depth, and strong aquifer permeability made it easy for pollutants to enter the aquifer, resulting in high groundwater vulnerability in the northwest of Santanghu Town, the southeast of Dahongliuxia Township, and Kuisu Town in Barkol County. The groundwater pollution load and groundwater functional value were generally low, whereas the point source and non-point source pollution caused by industrial and agricultural production and life would increase the groundwater pollution load in local areas, and the human economic activities and habitat quality levels would affect the distribution of high groundwater function value areas. Groundwater pollution risk was generally low; very high and high pollution risk areas only accounted for 6.8% of the study area, mainly distributed in Naomaohu Town and Yanchi Town of Yiwu County, Kuisu Town, Shirenzi Township, Huayuan Township of Barkol County, and Hongshan Farm of Corps. The shallow groundwater depth, strong permeability of soil surface and vadose zone media, poor adsorption capacity, and concentrated distribution of pollution sources made it easy for pollutants to migrate and enrich in these areas. Under the dual influence of high vulnerability and high pollution load of groundwater, the risk of groundwater pollution in local areas increased. Affected by human activities, there was a certain spatial agglomeration of groundwater pollution risk, and the overall trend was from northwest to southeast. The results of groundwater pollution risk assessment provided a scientific reference for the division of groundwater pollution prevention and control areas.

[Preparation and luminescent performance of Tb3+ doped SiO2 core-shell nanoparticles].

The authors synthesized the core-shell nanoparticles of SiO2-coated SiO2:Tb3+ by using sol-gel method (SiO2:Tb3+ @SiO2), and studied the influence of core-shell ratio and preparation craftwork on its luminescence properties. The photograph of TEM and EDS showed that SiO2:Tb3+ were coated successfully by SiO2. The authors found that the samples of SiO2:Tb3+ @SiO2 prepared by mixing of core and shell after shell aging with the ratio of core/shell being 1.2 g/25 mL had the stronger fluorescence intensity. Time-resolved spectra showed that the SiO2:Tb3+ @SiO2 had longer fluorescence life time than SiO2:Tb3+.

Nucleos(t)ide Analogues for Reducing Hepatocellular Carcinoma in Chronic Hepatitis B Patients: A Systematic Review and Meta-Analysis.

Background/Aims: Studies have shown that nucleos(t)ide analogue (NA) treatment can reduce the risk of hepatocellular carcinoma (HCC) in chronic hepatitis B (CHB) patients, but it is unclear which NA is most effective. We performed a meta-analysis and systematic review comparing the efficacies of NAs in CHB patients. Methods: We searched literature databases for randomized controlled trials (RCTs) and observational studies that analyzed the hepatic biochemical response, virological response, seroconversion rate, drug resistance rate, and HCC incidence rate in CHB patients treated with NAs. Meta-analyses were performed with RevMan and Stata/SE software. Results: Twelve cohort studies and one RCT were selected, in which entecavir (ETV), lamivudine (LAM), telbivudine (LdT), and/or tenofovir disoproxil fumarate (TDF) were evaluated in CHB patients. The meta-analysis showed that ETV was superior to LAM with regard to the HCC incidence (p<0.001), biochemical response (p=0.001), virological response (p=0.02), and drug resistance (p<0.001), and ETV was superior to LdT with regard to the virological response (p<0.001) and drug resistance (p<0.001). We found no significant difference between ETV and TDF with regard to the HCC incidence (p=0.08), biochemical response (p=0.39), virological response (p=0.31), serological conversion (p=0.38), or drug resistance (p=0.95). NA-treated patients with pre-existing cirrhosis had a 5.49 times greater incidence of HCC than those without cirrhosis (p<0.001). Conclusions: ETV or TDF should be used for long-term first-line monotherapy in CHB patients according to the current guidelines. Standardized protocols are needed for future studies of ETV and TDF to facilitate conclusive comparisons. Patients with cirrhosis are at significantly elevated risk for HCC, despite the benefits of NA treatment.

[Differential expression of immediately early gene c-fos in THP-1 macrophage subtype polarization].

Objective: To investigate the expression of immediate early gene c-fos in THP-1 macrophage subtype polarization. Methods: PMA was used to induce the polarization of THP-1 monocytes to macrophages, and the expression of c-fos in the polarization process was observed. After PMA treatment, LPS or IL-4 were used alone to induce the polarization of THP-1 macrophages to the M1 or M2 subtypes. Subsequently, real-time quantitative PCR and western-blot were used to analyze the changes in the expressions of the cell subtype markers CD274, CD86 and CD163. Meanwhile, the expression of c-fos in the polarization process was observed dynamically. Results: The levels of c-fos protein and mRNA expressions were up-regulated during PMA-induced polarization of THP-1 monocytes. The protein and mRNA expressions of c-fos were significantly decreased during the polarization of THP-1 cells into M1 macrophages induced by LPS. The specific markers showed the characteristics of M1 macrophages polarization at 24 h (CD86 protein increased, CD274 and CD163 protein decreased). The protein and mRNA expressions of c-fos were significantly increased during the polarization of THP-1 cells into M2 macrophages induced by IL-4. The specific markers showed the characteristics of M2 macrophages polarization at 24 h (CD86 protein decreased, CD274 and CD163 protein increased). Conclusion: C-fos plays an important role in the polarization of THP-1 monocytes to macrophages. Moreover, it may be involved in the regulation of macrophage subtype polarization, by inhibiting the formation of M1 macrophage and promoting the polarization of macrophages to the M2 subtype.

Staphyloxanthin: a potential target for antivirulence therapy.

Staphylococcus aureus is an important and common Gram-positive bacteria which causes clinical infections and food-poisoning cases. Therapeutic schedules for treatment of S. aureus infections are facing a challenge because of the emergence of multidrug resistance strains. It is urgent to find new antiinfective drugs to control S. aureus infection. S. aureus strains are capable of producing the golden carotenoid pigment: staphyloxanthin, which acts as an important virulence factor and a potential target for antivirulence drug design. This review is aimed at presenting an updated overview of this golden carotenoid pigment of S. aureus from the biosynthesis of staphyloxanthin, its function, and the genes involved in pigment production to staphyloxanthin: a novel target for antivirulence therapy.